With shares of the diet shake company tumbling 19.1 percent over the last two days — on top of a 52 percent decline last year — the billionaires who famously faced off against Bill Ackman and his $1 billion short are getting bloodied.

For example:

Carl Ichan, Herbalife’s top shareholder, with a 19 percent stake, is now carrying a $100 million paper loss in his investment.

Bill Stiritz — the executive chairman of cereal-maker Post Holdings — who at least until this week, was Herbalife’s fourth-largest shareholder with an 8.15 percent stake, had paper losses of $200 million to $250 million, according to estimates by The Post.

Paul Sohn, the architect of the George Soros charge into Herbalife — an investment that made the billionaire the company’s fifth-largest investor — has seen his reputation just a little more sullied than before the investment in the LA company.

Sohn left Soros Fund Management in November, The Post learned late Monday, shortly after the fund sold its last Herbalife shares — possibly getting out with a marginal profit.

Sohn left the firm for an undisclosed “business opportunity,” according to a source.

Sohn famously encouraged other hedgies to join his Herbalife wager, saying that Soros could “break the back of Ackman.”

His antics led regulators to investigate Soros. The probe, and the stock’s slide, put Sohn in an uncomfortable position at the firm, sources said.

The Herbalife woe over the last two trading days — with volume four times the average — left shares at $30.42, a two-year low.

The pattern of trading on Monday and Tuesday has led many market players to speculate that Stiritz has been methodically unloading his entire 7.5 million-share stake.

Although that could not definitely be determined, more than 10 million shares traded in the past two days.

While the stock was sinking, trading in put options that expire this Friday also increased — as if to protect against an impending loss, sources said.

If Stiritz has sold, securities rules require him to disclose the sales “promptly” — which investors argue is a good reason to blow it all out in two days.

Activist hedge fund investor Dan Loeb, who bought into Herbalife in the low $30s, got out by mid-February 2013, with a $50 million gain.

Sohn declined to comment. Soros Fund Management said his departure was unrelated to Herbalife.